SO said he’d choose me over the baby!

Being a high risk pregnancy and having already had a still born during birth, my SO and I touched base of the risks and what would happen if this should arise again and he said he’d “choose me over the baby because we can make another one”

I was utterly heartbroken because I’ve had a still born already and would completely be devastated at the though of going through this a second time, waking up without my baby.

I for sure thought he’d choose the baby and not me, and I know it’s selfish for me to ask of that because he’d be left as a single father all alone with a baby but I’ve lived my life, I got to see 31!

His response “well you need to get it in writing then because I’m choosing you” How does one even do such a thing?

This is a touchy subject and I just need some thoughts or advice on how to handle this as me and him have different views that won’t change!